It more particularly concerns a hinge assembly for a vehicle seat, comprising:                first, second, and third frames assembled to pivot relative to each other on a first axis,        a hinge mechanism connecting the first and third frames, said hinge mechanism being adapted to adjust an angular usage position of the first frame relative to the third frame,        a first lock assembled on the first frame to move between a locked position, in which said first lock immobilizes the first frame relative to the third frame in said usage position, and an unlocked position, in which said first lock allows the first frame to pivot relative to the third frame,        a first control device adapted to move the first lock between said locked position and said unlocked position.        
Document FR-A-2 888 173 describes an example of a known hinge assembly and seat of this type.
The aim of the invention is to improve motor vehicle seats of this type, particularly to enable locking the backrest in the forward tilted position.